1. Field of the Invention
The present invention relates to a coupling apparatus for coupling two members, e.g., hoses such as fire hoses, or a pump and a hose to each other.
More specifically, the present invention is constituted by a pair of couplers which have the same structure and are complementary. These couplers are axially fitted and coupled to each other.
2. Description of the Related Art
As a hose coupling apparatus for coupling fire hoses to each other, conventionally, ones which are disclosed in, e.g., Jpn. UM Appln. KOKOKU Publication No. 63-37593, Jpn. UM Appln. KOKAI Publication No. 64-53593, Jpn. UM Appln. KOKOKU Publication No. 2-34549, Jpn. UM Appln. KOKAI Publication No. 59-193443, and the like are known.
Each of Jpn. UM Appln. KOKOKU Publication No. 63-37593 and Jpn. UM Appln. KOKAI Publication No. 64-53593 discloses hose couplers having substantially the same structures.
In these couplers, a rotational ring is rotatably fitted on the outer circumferential surface of a cylindrical main body of each coupler, and a pair of locking pawls and a pair of wedge-shaped projecting ridges are provided to this rotational ring. When the two rotational rings are rotated, the locking pawls of one rotational ring are fitted with the wedge-shaped projecting ridges of the other rotational ring, thereby coupling the pair of couplers to each other.
The hose couplers disclosed in each of Jpn. UM Appln. KOKOKU Publication No. 2-34549 and Jpn. UM Appln. KOKAI publication No. 59-193443 have basically and substantially the same structures and are constituted by a male coupler and a female coupler. A locking projection is formed on the male coupler, and a locking pawl to fit on the locking projection is provided to the female coupler. When the male and female couplers are axially abutted against each other, the locking projection and the locking pawl are fitted to each other, thereby coupling the male and female couplers.
According to the former couplers, the pair of couplers are positioned and abutted against each other, and the rotational rings are rotated to fit the locking pawls on the wedge-shaped projecting ridges. Operations for coupling and disconnecting the couplers are cumbersome. Thus, these couplers are not suitable as couplers which must quickly couple hoses, e.g., fire hoses, or disconnect them.
The fire hose is often dragged during fire fighting. If the locking pawls project as in the former coupler, the locking pawls tend to be interfered by obstacles. Then, the locking pawls may be deformed or broken to undesirably disconnect the couplers. In the former couplers, since the locking pawls project from the rotational rings in the cantilevered manner, when a high pressure is applied to the hose, a bending load acts on the locking pawl portions to bend the locking pawls. Then, the clamped state of the couplers can be loosened, leading to water leakage.
According to the latter couplers, the locking projection and the locking pawl are fitted to each other only by axially abutting the male and female couplers against each other, thereby coupling the male and female couplers. The coupling and disconnecting operations of the couplers are simple when compared to the operations of the former couplers. However, in the latter couplers, disengaging pieces for disengaging the locking projection from the locking pawls are provided to be axially slidable. When the fire hose is dragged during fire fighting, the disengaging pieces are slid to disengage the locking projection from the locking pawl, so that these couplers may be undesirably separated from each other.
In the latter couplers, a male coupler is attached to one end portion of the hose, and a female coupler is attached to the other end portion of the hose. When a plurality of hoses are to be connected to obtain an extended hose, the male coupler of one hose must be coupled to the female coupler of the other hose. In particular, when the latter couplers are applied to the couplers for fire hoses, if a plurality of hoses are to be straightened and coupled to each other in a haste, the two couplers sometimes turn out to be male couplers and thus cannot be coupled to each other. In the latter couplers, two types of metal members, i.e., female and male couplers, must be manufactured, leading to an increase in cost.